(1) Field of the Invention
This invention relates to a process for the preparation of a titanium-based catalyst component (hereinafter referred to simply as a catalyst component) of a catalyst for use in the polymerization of .alpha.-olefins composed of the titanium-based catalyst component and an organo aluminium compound, where polymerization includes homopolymerization and copolymerization thereof.
That is, this invention relates to a process for the preparation of a catalyst component having such a high activity that when applied to the polymerization of .alpha.-olefins it serves to show a high activity, and stereoregular polymers can be obtained in high yields, and more particularly relates to a process for the preparation of a catalyst component, which comprises copulverizing for physicochemical treatment a magnesium halide with aluminium isopropoxide to form a first copulverization product, adding an electron donor compound to the first copulverization product for physicochemical treatment to obtain a second solid copulverization product, contacting the second solid copulverization product with a titanium halide in the liquid phase or in the gaseous phase to be reacted therewith, and washing a resulting reaction product with an inert organic solvent.
(2) Description of the Prior Art
A titanium halide is well known in the art as a catalyst component for use in the polymerization of .alpha.-olefins. However, in the polymerization with the titanium halide known as the conventional catalyst component, the yield of polymers per unit weight of the catalyst component or of titanium moiety in the catalyst component (hereinafter referred to simply as a polymerization activity per unit weight of titanium) is so low that the so-called deashing process for subsequently removing catalyst residues from the polymer product is indispensable in order to obtain an industrially applicable polymer product. In the deashing process, alcohols or chelating agents are used in large amounts, so that the deashing process needs an apparatus for recovery thereof as well as the deashing apparatus itself, and consequently has many problems accompanying therewith relative to resources, energy, and the like. Thus, the deashing process raises a great problem to be solved urgently in the art. A number of studies and suggestions have been made for enhancing the polymerization activity per unit weight of titanium in the catalyst component, so that the complicated deashing process may be dispensed with.
Especially as a recent tendency, a large number of suggestions have been made such that the polymerization activity per unit weight of titanium in the catalyst component is remarkably enhanced in the polymerization of .alpha.-olefins with a catalyst component prepared by supporting a transition-metal compound as an active ingredient such as a titanium halide on a porous carrier material so that the active ingredient may act effectively. Further, various suggestions have been made on improvements in carrier materials themselves, effects on the improvement in method of supporting, addition of a third ingredient, and the like.
For example, Japanese Patent Publication No. 41676/'72 discloses a process for the preparation of a catalyst component in which a halide of magnesium or zinc, which is pulverized for activation, is either suspended in liquid titanium tetrachloride to support titanium thereon followed by washing with an organic solvent, or brought into contact with an organic solvent for treatment beforehand followed by evaporating the solvent for removal and then suspended in liquid titanium tetrachloride to support titanium thereon followed by washing with an organic solvent, and thereafter the resulting reaction mixture obtained by either one of the procedures as above is subjected to a solid-liquid separation procedure to obtain a solid reaction product for use in the polymerization of .alpha.-olefins as the catalyst component. The aforesaid process shows a great effect on the polymerization activity per unit weight of titanium in the catalyst component, but has such a drawback that the yield of stereoregular polymers, which may also be referred to as an overall yield of crystalline polymers, remains at a very low level.
As a process to eliminate drawbacks above described, Japanese Patent Laid-open Publication No. 126590/'75 discloses a process for the preparation of a catalyst component, in which a magnesium halide is brought into contact with an electron donor compound as a third ingredient specifically with an aromatic carboxylic acid ester by a mechanical means to form a solid reaction product, and the solid reaction product thus obtained is brought into contact with titanium tetrachloride in the liquid phase or in the gaseous phase to obtain the catalyst component. According to this process, the polymerization activity per unit weight of titanium is increased to such an extent that the deashing process may satisfactorily be dispensed with for practical use thereof. However, the yield of stereoregular polymers remains at an unsatisfactory level to be insufficient for industrial practical use.
As a process to improve the aforesaid process, Japanese Patent Laid-open Publication No. 87489/'77 discloses a catalyst component for the polymerization of .alpha.-olefins, which is obtained as the most preferable embodiment thereof by copulverizing a compound of a metal selected from aluminium, tin, and germanium containing at least an organic group or a halogen with a halogen containing magnesium compound in the presence of an organic acid ester to be brought into contact with each other, and contacting the resulting copulverization product with a titanium compound for reaction. This catalyst component shows a considerably favorable effect on the polymerization activity per unit weight of titanium and the yield of stereoregular polymers compared with that in the aforesaid process, but still remains unsatisfactory for the demand in the highly developing technical field to be improved taking into consideration polymerization characteristic values such as the yield of polymers per unit weight of a catalyst component (hereinafter referred to as a polymerization activity per unit weight of a catalyst component) and the yield of stereoregular polymers.
All the catalyst components described above have a tendency to put too much emphasis on increase in the polymerization activity per unit weight of titanium in the catalyst component, and consequently the yield of stereoregular polymers is sacrified therefor to some extent. Further, the fact that a less emphasis is put on the polymerization activity per unit weight of the catalyst component is responsible for having caused adverse effects due to other residues than titanium moiety residue on the polymer product.
Titanium has been the primary residue to be avoided among catalyst residues which have adverse effects on the polymer product. Accordingly, efforts have been made for dispensing with the deashing process for the removal of catalyst residues by increasing the polymerization activity per unit weight of titanium with considerably favorable results. This idea itself of dispensing with the deashing process is beyond question. However, it is well known in the art that other materials contained in the catalyst component than titanium such as ingredients of carrier materials in the aforesaid supported catalyst component, for example, have unfavorable effects on the polymer product and apparatus for polymerization.